1). Field of the Invention
This invention relates to a polymer memory of the kind having a ferroelectric polymer memory material, and to its method of manufacture.
2). Discussion of Related Art
A polymer memory typically has a plurality of conductive word lines extending parallel to one another in an x-direction, and a plurality of bit lines extending parallel to one another in a y-direction, such that an array of cells is created, each cell being where a respective word line crosses over a respective bit line. Information can be written to or be read from one of the cells by selecting the word and bit lines that cross over the cell, and then providing a voltage to or sensing a current from one of the word or bit lines. A ferroelectric polymer memory material may, for example, space the word lines from the bit lines and may have its conductivity change at select cells by applying a select voltage over respective word and bit lines crossing over the select cells.
As computers require more memory, the need exists to include a larger number of cells in a given area, thus necessitating the need for equipment upgrades from one generation of polymer memory to the next. Some polymer memories have a total of 12 layers of metal lines, with 8 layers of ferroelectric polymer memory material between the layers of metal lines. The traditional belief has been that tooling has to be upgraded in order to photolithographically form all 12 layers of metal lines. This can lead to an equipment upgrade ratio of 40% or more, which is generally regarded as being too high when transitioning from one memory product to the next.